我不确定如何准确编码，但我可以肯定地说，我相信它比我的代码所表明的更好。
我希望来自父类的extract();变量，并且这些变量可以自动用于子类中的函数。
目前，我必须调用extract（）;每个子类函数内的函数，以使变量可用。这就是我试图减少的，extract（）;每次只在儿童班内打电话一次。
我是__construct（）的新手;因为我开始时只是静态调用函数。但我试着研究并理解这一点，但我只能在网上找到如何将单个变量传递给__construct（）;中的其他函数的文章。我找不到任何关于如何一次传递多个变量的文章。特别是使用extract（）;。
可以这样做吗？
我的最终目标只是减少＆＃34; parent :: ＆＃34;对于子类中的每个var。因此，在需要时，我可以提取变量，只需编写$var而不是parent::$var。
// ----------------------------------------------------------------------------------------------------
// Concept One
// ----------------------------------------------------------------------------------------------------
class Parent_Vars {
public static function get_vars() {
$vars = array(
'var_1' => 'var_1',
'var_2' => 'var_2',
'var_3' => 'var_3',
);
return $vars;
}
}
class Parent_Vars extends class Child_Vars {
public static $instance;
static function getInstance() {
if (!self::$instance) {
self::$instance = new self;
}
return self::$instance;
}
public function __construct() {
parent::get_vars();
}
// This method DOES NOT work
public static function echo_var_method_1() {
//extract(parent::get_vars()); If I uncomment this, my vars below will work
// But I don't want to call extract(parent::get_vars()); for every function I need.
// I would like the vars to already be available from the __construct();
echo $var_1; // returns error = undefined var
echo $var_2; // returns error = undefined var
echo $var_3; // returns error = undefined var
echo parent::$var_1; // Works, but I'm trying to reduce writing parent:: everytime
echo parent::$var_2; // Works, but I'm trying to reduce writing parent:: everytime
echo parent::$var_3; // Works, but I'm trying to reduce writing parent:: everytime
}
// This method DOES work
public static function echo_var_method_2() {
extract(parent::get_vars()); // I'm trying NOT to call the var extract for each function, but for the whole class at once
echo $var_1; // echoes "var_1" !! No need to write parent:: everytime for the vars
echo $var_2; // echoes "var_2" !! No need to write parent:: everytime for the vars
echo $var_3; // echoes "var_3" !! No need to write parent:: everytime for the vars
}
}
$object = new Child_Vars();
Child_Vars::echo_var_method_1();
Child_Vars::echo_var_method_2();
// ----------------------------------------------------------------------------------------------------
// Concept Two - just slightly different with the parent class having its own __construct(); and the child __construct(); calling the parent __construct();
// ----------------------------------------------------------------------------------------------------
class Parent_Vars {
public function __construct() {
extract(self::get_vars());
}
public static function get_vars() {
$vars = array(
'var_1' => 'var_1',
'var_2' => 'var_2',
'var_3' => 'var_3',
);
return $vars;
}
}
class Parent_Vars extends class Child_Vars {
public static $instance;
static function getInstance() {
if (!self::$instance) {
self::$instance = new self;
}
return self::$instance;
}
public function __construct() {
parent::__construct();
}
// This method DOES NOT work
public static function echo_var_method_1() {
//extract(parent::get_vars()); If I uncomment this, my vars below will work
// But I don't want to call extract(parent::get_vars()); for every function I need.
// I would like the vars to already be available from the __construct();
echo $var_1; // returns error = undefined var
echo $var_2; // returns error = undefined var
echo $var_3; // returns error = undefined var
echo parent::$var_1; // Works, but I'm trying to reduce writing parent:: everytime
echo parent::$var_2; // Works, but I'm trying to reduce writing parent:: everytime
echo parent::$var_3; // Works, but I'm trying to reduce writing parent:: everytime
}
// This method DOES work
public static function echo_var_method_2() {
extract(parent::get_vars()); // I'm trying NOT to call the var extract for each function, but for the whole class at once
echo $var_1; // echoes "var_1" !! No need to write parent:: everytime for the vars
echo $var_2; // echoes "var_2" !! No need to write parent:: everytime for the vars
echo $var_3; // echoes "var_3" !! No need to write parent:: everytime for the vars
}
}
$object = new Child_Vars();
Child_Vars::echo_var_method_1();
Child_Vars::echo_var_method_2();
答案 0 :(得分：1)
更新
class MyClass
{
public function __construct($data)
{
foreach($data as $key => $value){
$this->$key = $value
}
}
}
class MyClass2 extends MyClass
{
public function __get($name) {
return $this->$name;
}
}
$instance = new MyClass2($variableArray);
$xtractedVar = $instance->variableKey;
您可以使用此基本原则来解决并找到所需的解决方案。
答案 1 :(得分：0)
我不认为你非常了解OO并试图采用非OO的思维方式。 PHP中的对象（以及大多数其他基于类的OO语言）是数据的集合以及操纵该数据的相关方法集合。在创建给定类的子类时，可以创建一种新类型的对象，该对象扩展了变量集合和适用方法的集合。
您似乎也很难理解类变量（所有类共有）和实例变量（其值对于给定的类实例是唯一的变量）之间的区别。
对于实例变量，任何非私有变量都可以通过$ this自动用于子类。
class SuperClass {
protected $var = "";
public function showVar ()
{
echo $this -> var . PHP_EOL;
}
public function setVal ($newVal)
{
$this -> var = $newVal;
}
}
class SubClass extends SuperClass {
public function showVarInString ()
{
echo "Hello, I'm a subclass with value " . $this -> var;
}
}
$a = new SuperClass ();
$b = new SubClass ();
$a -> setVal (1);
$b -> setVal (4);
$a -> showVar (); // "1"
$b -> showVar (); // "4"
$b -> showVarInString (); // "Hello, I'm a subclass with value 4"
类变量，即静态变量，对于类的所有实例都是通用的，可以使用static ::而不是$ this
进行访问class SuperClass
{
protected static $var = 1234;
}
class SubClass extends SuperClass
{
public function showVar ()
{
echo static::$var . PHP_EOL;
}
}